Use of benthic diatom communities to evaluate water quality in rivers of southern Poland

Biological and chemical data were processed to estimate trophic stage and degree of pollution in several streams and rivers in southern Poland. The majority were eutrophic and some of them heavily polluted; only a few were oligo-mesotrophic. The differences in the water quality of the rivers were reflected by different types of diatom community and also by the values for some diatom indices, which were calculated using the latest version of the 'Omnidia' database software. Except for the Sládeček's index, all diatom indices correlated significantly with organic load (COD), oxygen concentration, conductivity and most of the measured ions. Some indices showed a significant negative correlation with trophic level (expressed by NH₄-N and PO₄-P). In general, IPS (Specific Pollution Sensitivity Index) and GDI (Generic Diatom Index) indices gave the best results. Among the investigated diatom communities, only a few taxa indicated oligo-mesotrophy and oligo-β-mesosaprobity. Most of the sites were characterised by a greater relative contribution of eutraphent and tolerant ones as well as α-mesosaprobic and polysaprobic diatoms. This study suggests that the structure of benthic diatom communities and diatom indices, especially GDI, can be applied for monitoring rivers in Poland. This revised version was published online in June 2006 with corrections to the Cover Date.